chore: apply new documentation style.

Co-authored-by: jbdoumenjou <jb.doumenjou@gmail.com>

docs/content/contributing/advocating.md

@@ -5,6 +5,6 @@ Spread the Love & Tell Us about It
 
 There are many ways to contribute to the project, and there is one that always spark joy: when we see/read about users talking about how Traefik helps them solve their problems.
 
-If you're talking about Traefik, [let us know](https://blog.containo.us/spread-the-love-ba5a40aa72e7) and we'll promote your enthusiasm!
+If you're talking about Traefik, [let us know](https://blog.traefik.io/spread-the-love-ba5a40aa72e7) and we'll promote your enthusiasm!
 
 Also, if you've written about Traefik or shared useful information you'd like to promote, feel free to add links in the [dedicated wiki page on Github](https://github.com/traefik/traefik/wiki/Awesome-Traefik).

docs/content/contributing/documentation.md

@@ -10,7 +10,7 @@ Let's see how.
 
 ### General
 
-This [documentation](https://docs.traefik.io/) is built with [mkdocs](https://mkdocs.org/).
+This [documentation](https://doc.traefik.io/traefik/) is built with [mkdocs](https://mkdocs.org/).
 
 ### Method 1: `Docker` and `make`
 

docs/content/contributing/submitting-issues.md

@@ -14,7 +14,7 @@ To save us some time and get quicker feedback, be sure to follow the guide lines
 
     For end-user related support questions, try using first:
 
-    - the Traefik community forum: [![Join the chat at https://community.containo.us/](https://img.shields.io/badge/style-register-green.svg?style=social&label=Discourse)](https://community.containo.us/)
+    - the Traefik community forum: [![Join the chat at https://community.traefik.io/](https://img.shields.io/badge/style-register-green.svg?style=social&label=Discourse)](https://community.traefik.io/)
 
 ## Issue Title